In response to ecological concerns, the Federal Environmental Protection Agency (EPA) has developed regulations regarding leakage from underground storage tanks. To assist in the detection of leakage, observation wells and monitoring wells are often installed near such tanks. An observation well, known in the art, is a well located within an area around a tank which was excavated during installation of the tank. A monitoring well on the other hand is known in the art as a well outside of the tank excavation area (some of which extend below the water table). Observation and monitoring wells typically have similar constructions. The term "monitoring well" is used herein to refer to both observation wells and monitoring wells, and also to refer to other known wells for monitoring waste areas. Furthermore, hereinafter fluids, vapors, liquids, and gases are collectively referred to as fluids.
An often encountered problem in the art is presented when leaking or leeching processes occur at waste area sites. In such circumstances, pollutants or toxic materials soak into the earth thereby contaminating the immediate vicinity and posing a potential threat. It is beneficial in such situations to have a well present for monitoring the waste area so as to quickly detect such leaks.
The underlying purpose of many monitoring wells is to protect the quality of the underground water table often used as a drinking water supply or other similar purposes. Strategic placement of a number of monitoring wells around storage, waste area, processing, or manufacturing sites containing pollutants or toxic materials, and subsequent periodic sampling of fluids from the monitoring wells, gives an early indication of underground water supply contamination in the immediate vicinity of the potential threat. Samples taken from the monitoring wells on a periodic and systematic basis are tested for their fluid quality. If a leak or leeching process is occurring or has occurred at the storage, waste, manufacturing, or processing site, the effects of pollutant intrusion into the underground water supply or into the earth are discovered in their initial stages by testing the well samples. A key to the success of such a monitoring system lies in a program of systematic and continuous recovery of fluid samples from the monitoring wells and in maintaining the integrity of such monitoring wells from external events and/or substances which may potentially cause erroneous or biased readings from fluid quality analysis done on the recovered samples.
U.S. Pat. No. 4,942,923 to Geeting discloses an apparatus for isolating a testing zone in a bore hole screen casing. The isolated test zone is defined between lower and upper plug members with a fluid carrying tube connected to the upper plug member for accessing and sampling fluid within the test zone. Unfortunately, the apparatus of the '923 patent suffers from at least the following problems. Firstly, the '923 apparatus is an internal device disposed inside of the conduit (i.e. well casing) itself. In other words, it is not located at the end or top of a conduit, but instead is disposed interior the conduit at a predetermined depth at which it is desirable to access and sample fluid. Internal devices such as that disclosed in the '923 patent are limited to particular depths, difficult to access, and requires an undesirably large amount of labor to install. Additionally, the '923 patent apparatus is non-locking increasing susceptability to tampering. In view of this, it is clear that there exists a need in the art for a sampling plug which may be placed on a conduit end (e.g. the top of a well casing) so that it is both easy to access when it is desired to take samples, and simple to install.
Another problem with the device of the '923 patent is that the device itself (not including the sampling tube attached to it) does not provide as effective a seal as would be desired in view of the fact that the bore in the upper plug member remains open at all times. In view of this, it is apparent that there exists a need in the art for a sampling plug which, when not in use, functions as a complete fluid seal in of itself so as to keep fluid from entering or leaving the conduit or well interior when samples are not being obtained.
U.S. Pat. No. 5,348,085 discloses a mechanical plug device for sealing a well casing. The plug device of the '085 patent includes an adjustable and tamper resistant sealing structure which includes a turning member and cooperating locking member which permits access to a sampling aperture. The monitor plug of the '085 patent may be secured to the top of a well casing and permits sampling access without requiring the removal of the plug. When sampling is desired by way of the plug of the '085 patent, a latch member must first be pivoted to an upward position, and then a threaded plug must be removed from the sampling conduit or port in order to provide sampling access to the well interior. Unfortunately, this process required for sampling is both time consuming and difficult. Furthermore, the closing of the sampling port by way of the threaded plug is not as effective as would otherwise be desired in view of the fact that proper closing of the conduit requires both the plug being tightly screwed into the conduit opening and the threads of the mating connection being in "good shape". Additionally, the well interior is undesirably exposed to the outer atmosphere upon removal of this threshold plug. This exposure to the atmosphere contaminates the integrity of the well interior thus hurting the sampling process. In view of this, it is clear that there exists a need in the art for a well monitor plug device which allows for simpler and more efficient sampling of the well interior without having to remove the plug itself.
It is a purpose of this invention to fulfill the above-described needs in the art, as well other needs in the art which will become apparent to the skilled artisan once given the following disclosure.